code: def test_call_works_when_root_directory_is_specified(self) -> None:
      root_dir = TEST_BIN_PATH.parent.parent
  
      mapper = FileMapper(root_dir)
  
      pathname = TEST_BIN_PATH.relative_to(root_dir)
  
      output = mapper(pathname)
  
      assert output["path"] == pathname
  
      self.assert_file(output, TEST_BIN_PATH)
  
file_path: fairseq2/tests/unit/data/test_file_mapper.py
imports: from pathlib import Path
  from typing import Any, Final, Optional
  import pytest
  from fairseq2.data import FileMapper, FileMapperOutput
label_desc: Use image node_id 4 for calling the TestFileMapper obj's underlying member method code with example usage: obj.test_call_works_when_root_directory_is_specified() without return types